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4372. NGC 4833 BV photometry
- ID:
- ivo://CDS.VizieR/J/A+AS/109/479
- Title:
- NGC 4833 BV photometry
- Short Name:
- J/A+AS/109/479
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A color-magnitude diagram for the galactic globular cluster NGC 4833, based on the photographic BV photometry of about 868 stars in a 12'x12' field with an automatic measuring machine, is presented. It reaches the cluster main sequence turn-off at V=~19.2mag; the difference in V magnitudes between the turn-off and the horizontal branch being normal.
4373. NGC 6139 BV photometry
- ID:
- ivo://CDS.VizieR/J/A+A/583/A69
- Title:
- NGC 6139 BV photometry
- Short Name:
- J/A+A/583/A69
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Information on globular clusters (GC) formation mechanisms can be gathered by studying the chemical signature of the multiple populations that compose these stellar systems. In particular, we investigate the anti-correlations among O, Na, Al, and Mg to explore the influence of cluster mass and environment on GCs in the Milky Way and in extragalactic systems. We present here the results obtained on NGC 6139, which, on the basis of its horizontal branch morphology, has been proposed to be dominated by first-generation stars. In our extensive study based on high-resolution spectroscopy, the first for this cluster, we found a metallicity of [Fe/H]=-1.579+/-0.015+/-0.058 (rms=0.040dex, 45 bona fide member stars) on the UVES scale defined by our group. The stars in NGC 6139 show a chemical pattern normal for GCs, with a rather extended Na-O (and Mg-Al) anticorrelation. NGC 6139 behaves as expected from its mass and contains a large portion (about two thirds) of second-generation stars.
- ID:
- ivo://CDS.VizieR/J/AJ/106/66
- Title:
- NGC 1560 BVRI CCD photometry
- Short Name:
- J/AJ/106/66
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present BVRI CCD photometry of ~600 stars in the central region of a resolved spiral galaxy NGC 1560 which is seen almost edge-on, apparently located in the IC 342 group. The V-(B-V) diagram shows a dominant group of significantly reddened blue plume stars consisting of young massive main-sequence and evolved blue supergiant stars. The tip of the blue plume is found to be at V~21 mag and (B-V)~0.4mag. The I-(R-I) diagram shows a large group of red supergiants the brightest of which are extending to I~19.5mag at (R-I)~1.1mag. The logarithmic slope of the V luminosity function of the blue plume stars is 0.69+/-0.10, similar to that for other nearby galaxies. The mean color of the blue plume stars is <(B-V)>=0.25+/-0.03mag. The total reddening, including both foreground and internal reddening, is estimated from the mean color of the blue plume stars, to be E(B-V)=0.40+/-0.10mag, whereas the foreground reddening based on the H I column density and faint galaxy counts is E(B-V)=0.16mag. Combining our results with those in the literature, we have obtained distance estimates using four methods: brightest blue stars [(m-M)_0_=27.11mag], brightest red stars [(m-M)_0_=27.02mag], B-band Tully-Fisher relation [(m-M)_0_=26.96mag], and H-band Tully-Fisher relation [(m-M)_0_=26.86mag]. These four estimates agree very well. Taking the average of these four estimates, we obtain a value for the true distance modulus to NGC 1560, (m-M)_0_=27.0+/-0.1mag, corresponding to a distance of 2.5+/-0.1Mpc.
4375. NGC 205 BVRI photometry
- ID:
- ivo://CDS.VizieR/J/AJ/112/1438
- Title:
- NGC 205 BVRI photometry
- Short Name:
- J/AJ/112/1438
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- BVRI/CCD photometry of ~2,300 stars in the central 2.2'x3.5' area of the dwarf elliptical galaxy NGC205 in the Local Group is presented. The color-magnitude diagrams of NGC 205 show: (1) a blue plume around (B-V)~0.0mag, extending up to V~19.3mag (M_V_~-5.4mag); and (2) a strong asymptotic giant branch (AGB) population, the brightest of which reaches I~19.0mag, 1.5 mag brighter than the tip of the red giant branch. BVRI photometry of three globular clusters (Hubble IV. V, and VI) is also presented. Hubble V is much bluer [(B-V)=0.37] than other globular clusters. This blue color of Hubble V leads to an estimate of the age, ~300Myrs. A V luminosity function for the blue stars has been derived: the logarithmic slope of the luminosity function for -5.7<M_V_<-3.2 is 0.64+/-0.12, which is similar to those of other nearby galaxies. The AGB stars extend to Mbol~-5.7mag, which is ~0.7mag brighter than those in NGC 185. The bolometric luminosity function of the AGB stars in NGC 205 is found to be flatter than that of the similar dwarf elliptical galaxy NGC 185, but similar to that of a bulge field 4' of the nucleus of M31. Surface photometry for the central area within R=50" is presented, showing that the colors get bluer as the galactocentric radius decreases except for the nucleus region within R=1.6" where the colors get redder inward. Star formation history in NGC 205 is briefly discussed.
- ID:
- ivo://CDS.VizieR/J/A+A/351/526
- Title:
- NGC 2172 CCD BVI photometry
- Short Name:
- J/A+A/351/526
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new CCD photometry for the young LMC cluster NGC 2172, giving B, V, I magnitudes for more than 600 stars within 70" from the cluster center, down to -approximately- V=21mag. After correction for completeness and field stars contamination, we discuss the cluster HR diagram and the MS luminosity function in the light of current evolutionary theories and in connection with the problem of cluster age.
- ID:
- ivo://CDS.VizieR/J/PASP/117/22
- Title:
- NGC 6318 CCD BVI photometry
- Short Name:
- J/PASP/117/22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present CCD BVI photometry for the southern open cluster NGC 6318. The sample consists of 9876 stars measured in an area of 13.6'x13.6', extending down to V~21.5mag. Star counts carried out within and outside the cluster region allowed us to estimate the cluster angular radius as 8'.
4378. NGC 1866 CCD photometry
- ID:
- ivo://CDS.VizieR/J/ApJS/71/25
- Title:
- NGC 1866 CCD photometry
- Short Name:
- J/ApJS/71/25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The first part of this paper is devoted to a new CCD investigation of stars in the field of the LMC cluster NGC 1866. Two main frames have been analyzed, one covering the cluster's central region and the other covering an area about 10' from the cluster's center, and data has been collected for 2207 objects. On this basis, a C-M diagram has been derived, which shows a well-developed blue sequence reaching a limiting magnitude of about V=21mag together with the already known sequence of the cluster's He-burning giants. A new feature in our data is represented by the evidence for a second group of less luminous giants clumping around V=19mag, which we interpret as field He-burning giants. The second part of the paper is devoted to a comparison of these data with theoretical calculations. On the basis of new evolutionary tracks we find that the composition Y=0.28, Z=0.02 already used by Becker and Mathews (1983ApJ...270..155B) offers an adequate fitting of the observed range in color spanned by cluster He giants. Theoretical isochrones for this composition have been produced and are compared with the observed distribution of cluster stars. A good agreement with the observed C-M diagram is achieved for a cluster age of the order of t=100Myr, whereas field stars appear to be significantly older, with ages of about 500 Myr or more. The distribution of cluster stars is studied, and both the luminosity function of the blue sequence (BS) and number of He giants relative to BS stars are examined. We find that both these cluster characteristics can be reproduced with a Salpeter slope for the initial mass function, overcoming previous difficulties raised by suggestions of a serious disagreement between theory and observations in this cluster. The Appendix reports data for the evolutionary models and for the corresponding isochrones, covering both the H- and He-burning phases
4379. NGC 6994 CCD photometry
- ID:
- ivo://CDS.VizieR/J/A+A/355/138
- Title:
- NGC 6994 CCD photometry
- Short Name:
- J/A+A/355/138
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- BVRI CCD photometry of 144 stars in the region of NGC 6994: positions, V magnitudes, (B-V), (V-R) and (V-I) colors.
- ID:
- ivo://CDS.VizieR/J/other/ApSS/361.126
- Title:
- NGC 6819 CCD UBV photometry
- Short Name:
- J/other/ApSS/361
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of CCD UBV observations of the open cluster NGC 6819. We calculated the stellar density profile in the cluster's field to determine the structural parameters of NGC 6819. Using the existing astrometric data, we calculated the probabilities of the stars being physical members of the cluster, and used these objects in the determination of the astrophysical parameters of NGC 6819. We inferred the reddening and metallicity of the cluster as E(B-V)=0.130+/-0.035mag and [Fe/H]=+0.051+/-0.020dex, respectively, using the U-B vs B-V two-colour diagram and UV excesses of the F-G type main-sequence stars. We fit the colour-magnitude diagrams of NGC 6819 with the PARSEC isochrones and derived the distance modula, distance and age of the cluster as mu_V=12.22+/-0.10mag, d=2309+/-106pc and t=2.4+/-0.2Gyr, respectively. The parameters of the galactic orbit estimated for NGC 6819 indicate that the cluster is orbiting in a slightly eccentric orbit of e=0.06 with a period of P_orb_=142Myr. The slope of the mass function estimated for the cluster is close to the one found for the stars in the solar neighbourhood.
